Max Levchin is onto his third business plan for Slide. Levchin's startup just signed a deal with content distributors Time Warner, Warner Bros., CBS, E!, Hulu and others to turn Slide's FunSpace application — formerly known as FunWall — into a video-sharing, video-distribution channel targeting social network users. Opening a New York sales office soon, Slide will sell ads against its partners' videos as well as share in some of their revenues. Levchin's investors say Slide is worth $550 million, but they're obviously investing in Levchin's ability to will Slide's 160 million users into a valuable asset, no matter how many times the company stumbles.At its founding, Slide was supposed to be a shopper's search engine. That model was dropped and before today's news, Slide's plan was to somehow charge advertisers for conversations its social network widget users had about brands. That was too gimmicky and unproven for Madison Avenue. One exec there told me he expected "Slide and [it's closest rival] RockYou will get weeded out." Now Levchin says: "Television is a world that advertisers love." More than widgets? Let there be no doubt. If Levchin can turn Slide into an old school brand advertising-supported business with massive scale he might just live up to his investors expectations. For perspective, remember that ad-supported Readers' Digest has half as many people as subscribers and a private equity firm bought it for $1.6 billion in 2007.